Are these (in desc) browser extensions safe? and are there any safe, free opensource vpn extension for the browser?

I'm going to assume you're using Firefox based on the 5th extension you mentioned.

As for the adblockers, I wouldn't install multiple as they can conflict with each other and cause issues. I and many other people use uBlock Origin as it is very customizable and you can add your own filters and blocklists to essentially block anything you want. I'm not sure if it works with YouTube though, as I use Invidious.

As for the others, I've used YTNS, CAD and Search by Image previously without any issues. I've never heard of the rest though.

For a free VPN, the only one I'd trust is ProtonVPN. Most others are either running some sort of scam, or are very unreliable. Their Firefox add-on is terrible however, and requires that you are subscribed to a paid tier, so you'd have to set it up in a different way.

If you're ever concerned about the privacy/security of a piece of open source software, there are tools available that can scan through the source code and check for tracking or malware. One of the great things about open source is that, if you know what you're doing, you can modify the source code yourself to suit your own needs.

Edit: Fixed broken links (I hope)

Remove every "AdBlocker" and install a real one, aka uBlock Origin. AdGuard is definitely a good extension but imo uBlock Origin is the way to go and using multiple have been proven to harm blocking capabilities.

I suggest going for addons recommended by Firefox.

For blocking ads and other annoying content, I suggest uBlock Origin. It allows you to customize your experience, and can have the same or better effect than some other extensions. It is also not recommended to use multiple ad blockers, as they may conflict with each other.

For deleting cookies, I recommend not using an addon, but the settings of Firefox. Under "Cookies and Site Data" you can choose to delete cookies on close and manage exceptions for the cookies you want to keep.

For translation, Firefox Translations is fine.

Search by Image, I never used but it is recommended.

I usually avoid "redirect skippers". As they can be as problematic as the initial problem itself. I cannot find FastForward in firefox and Skip Redirect is not recommended by firefox.

edit: spelling

Mullvad for the VPN. And you don't need the ,,AdBlocker for YT" and especially not ,,Ad Block Plus" combinef with ,,AdGuard" use one of those or switch to uBlock, but those I mentioned are safe (Excluding YTADBlocker, don't know that one)

the only addons you need for blocking ads on youtube are ublock origin and sponsorblock. multiple adblockers used together can and will cause conflicts and impair the ability to properly block things.